RATE COEFFICIENTS FOR THE REACTION OF CHLORINE ATOMS WITH FS(O 2 )O AND FS(O 2 )OCl AT 298 K

The kinetics of the recombination reaction Cl + FS(O 2 )O → FS(O 2 )OCl (1) has been studied by using an ArF excimer laser flash photolysis technique over the 25-950 mbar total pressure range of the bath gases He, N 2 and CF 4 at 298 K. The reaction was found to be essentially in the second-order regime. The derived limiting high-pressure rate coefficient is k 1,∞ =(1.3±0.3)x10 -10 cm 3 molecule -1 s -1 . For the reaction Cl + FS(O 2 )OCl → FS(O 2 )O + Cl 2 (2) a rate coefficient of k 2 = (2.1±0.9)x10 -11 cm 3 molecule -1 s -1 was measured. The ratio between both rate coefficients of 0.16 agrees very well with data determined by Vasini and Schumacher. Quantum chemical calculations carried out at the G3MP2//B3LYP/6311+G(3df) level of theory allow to determine an standard heat of formation of -136.5 kcal mol -1 for FS(O 2 )OCl. Rate coefficient calculations in the framework of the phase space theory, performed on a G3MP2B3 electronic potential, indicate that central forces mainly dominate the present recombination reaction.